If you are thinking about moving to another place or doing something that might alter your total energy bills for heating, you might wish to get well prepared and understand how large your costs will be.

This largely depends upon three variables: how large your room is, how large your heater is, and just how much electricity the heater uses.

In the following guide, we will tackle each of the aforementioned. Aside from that, we’ll also teach you how you can calculate KW needed to heat a room or any larger space that you might be using.

How to Calculate KW Required to Heat a Room

Apart from the room’s length and width, there are different aspects to take into consideration when calculating the number of KW is needed to heat a space. Anything in the ceiling height, the volume of the walls, as well as the dimensions of the windows into this adjustment of the house and the isolation around it are all equally crucial.

Luckily, there are several formulas you may use while making this calculation, and they tend to use unique elements for doing this. Hence, the margin of error will likely be minimal.

Most probably, your monthly power use will surpass 1,000 watts, which is equal to 1 kilowatt. Because of this, we’ll calculate the result in the form of watts, since it’s the same as kilowatts.

The Formula for Rooms with Regular Ceilings

Most ceilings in contemporary homes and flats are 8 ft high. If this is the situation in your house, you should measure the width and the amount of the space and multiply it to find the square surface step. Then, multiply it by 10.

By way of example, if your area is 25 feet wide, and 30 feet long, your area calculation is going to be 750 square feet. Multiply that number by 10, and you’ll get an estimate of 7500 watts being used hourly for heating it, which is equal to 7.5 kilowatts.

For a more precise measure, you might have the ability to include additional factors, but we will speak about them later in this article.

The Formula for Rooms with Ceilings Higher Than Eight Feet

The formula for calculating hourly kilowatt use for ceilings greater than eight feet is similar to the regular one, with a small change included. You won’t be required to multiply the square foot area dimensions by 10. Instead, you will replicate the ceiling height by 1.25, and then use the number you get.

Doing so is reasonable, actually. You’ll notice that from the first calculation, we are employed the number 10 if the ceiling height is 8 feet, and 8 times 1.25 equals 10.

For instance, the room dimensions are 25 feet in diameter and 30 feet in length, which is the same as the initial example. Only now, the ceiling height is 10 feet rather than eight.

First, you will calculate the square feet surface, which is 750 feet. Following that, you will multiply that number by 12.5 (10 feet ceiling height times 1.25-kilowatt usage). In the end, you’ll have an estimated 9.375 kilowatts used per hour of maintaining the room temperature warm.

Additional Factors and Methods

Simply utilizing one of the supplied methods probably won’t give you an specific number of kilowatts necessary to keep a room warm. However, since the formulas work flawlessly for places which have windows of standard _size and perfect isolations, you might be able to get a clearer picture of the exact result by implementing these variables.

Insert a few percentage points into the calculation if the windows are much larger than what the normal measure is. Also, you can certainly do exactly the exact same thing if you know that the area has insulating material scarcities.

For example, if you admit that the home lacks 10% insulating material, also, using the formula for calculating the kilowatt usage, you got to know the sum of 7500 watts per hour, you can add 10 percent to it. This will give you the estimated usage of 7500 + 750 watts an hour, summing up to 8250.

Ultimately, we advocate using online calculators when performing this. You will have to measure your area and perhaps know more information concerning the type of heater you’re using if you opt for this online method.


Congratulations! Now you know how to compute KW required to warm a space during cold periods. There are two chief formulas we have shown that you, which vary depending on the room ceiling height. Furthermore, you would be required to incorporate other factors into the equation to find the most precise results possible.

Obviously, there’s a simpler way to do this, and it is by using a number of the internet calculators. Last, the most exact way to know this is by heating the room for a month and then looking at the invoice to know exactly how much energy it requires.